Control apparatus for air conditioning and like systems

ABSTRACT

Control equipment for power-operated mechanism, such as an airconditioning system including circuitry for preventing the operation or re-operation of the compressor or other load until the expiration of a substantial predetermined interval of time after the compressor or load has been released. This equipment will prevent the frequent intermittent operation of the motor of a compressor if, for example, the thermostat or a switch or any other control element were jiggled or moved erratically. This equipment also prevents the operation of the compressor or other load unless, within a second predetermined time interval, the pressure in the supply line feeding fluid to the compressor or load has reached a desired or predetermined pressure. If the predetermined pressure has not been attained, the circuitry will release the compressor motor or load.

United States Patent Granieri et al.

CONTROL APPARATUS FOR AIR 51 Oct. 24, 1972 Primary Examiner-Herman J.Hohauser CONDITIONING AND LIKE SYSTEMS Attorney-Jefferson Ehrlich,Tennes I. Erstad an [72] Inventors: George John Granieri, Piscataway;Robert Crooks Edgvard Herbert Lefkowitz, Edison, ABSTRACT [73] Y Assign:The Tammi Cmpany, Mansfield, Control equipment for I power-operatedmechanism, Ohio such as an air-conditioning system including circuitryfor preventing the operation or re-operation of the Flledi 20, 1970compressor or other load until the expiration of a sub- [21] Appl 91,446stantial predetermined interval of time after the compressor or load hasbeen released. This equipment will prevent the frequent intermittentoperation of the E2 "307/141, 533: motor of a compressor if, forexample, the thermostat or a Switch or y other control element were [581of Search'318/ 484 or moved erratically. This equipment also preventsthe 307/293 141A" 317/141 operation of the compressor or other loadunless,

within a second predetermined time interval, the pres- [56] ReferencesCited sure in the supply line feeding fluid to the compressor UNITEDSTATES PATENTS or load has reached a desired or predetermined pressure.If the predetermined pressure has not been at- M g isy-t-gi i tained,the circuitry will release the compressor motor c ra e 0 load 3,439,1914/1969 Kraemer ..307/293 r 14 Claims, 3 Drawing Figures LPS TM 5 Ty 2 4-I SW! E T 1 l l H TIMER l I W I f E6 355 E3 52 I I L L l Kl K1. K3 -b RKE L L L J J J 2M L L2 L3 L m 62 6. w

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PATENTED 24 I97? 3. 700 9 l 4 saw 3 (1F 3 m INVENTORS, GEORGE J.GRANIERI 5 EDWARD H. LEFKOWITZ FEBYS W ATTORNEY CONTROL APPARATUS FORAIR CONDITIONING AND LIKE SYSTEMS This invention relates to timingapparatus for controlling the operation of a load or power-operatedequipment, such as a compressor motor which may be part of anair-conditioning system.

One of the difficulties often encountered, for example, inair-conditioning equipment, arises inadvertently from the frequent andintermittent operation of the equipment due to the repeated opening andclosure of the contacts of a thermostat or of a relay contact in thecircuit of the compressor motor or due to any other switching orvibratory element. By turning the compressor motor on and off frequentlydue, for example, to the improper operation of a relay contact or athermostat or other means, the compressor motor will be subjected toconsiderable unwarranted wear and tear due to the unnecessary startingand stopping of the compressor motor. This will reduce the life of thecompressor motor and, in due course, render the entire airconditioningsystem out-of-order. These factors may similarly adversely affect theoperation of a boiler system, or an .electrical elevator system, or anyother load. This invention will be generally described and exemplifiedwith respect to an air-conditioning system, but it is to be understoodthat the features of the invention are likewise applicable to any loadwhich may suffer or default from repeated inadvertent operations.

One of the principal objects of the presentinvention is to provideequipment which will prevent the inadvertent recurrent, intermittent andrepeated operations of a compressor motor of an air-conditioning systemor other load until a predetermined or first interval of time, such asfive minutes, has expired. Thus, in accordance with this objective, thecompressor motor will be brought into operation, or brought intoreoperation, only if the equipment has been kept idle for a substantialpredetermined interval of time, thereby to prevent the sudden operationor re-operation of the equipment.

Another of the objects of this invention is to provide equipment tostart and operate equipment, such as a compressor motor, as long as maybe desired, but to prevent any re-operation of the motor until theexpiration of a substantial delay interval before the motor may berestarted, thereby avoiding unwanted or inadvertent starting sequencesof the motor.

Another of the objects of this invention is to prevent the operation orre-operation of the compressor motor of an air-conditioning system orother load at the end of the prescribed interval of time unless therehas been a call for operation of the compressor motor in response to,for example, the actuation of the switch contacts of a thermostatpursuant to a demand for operation of the compressor motor and unlessthe fluid required for the system or load has reached a predeterminedpressure.

As already suggested, this invention is provided to prevent theoperation or re-operation of the motor of an air-conditioner unless asufiicient delay interval has expired. If, after the predeterminedinterval of time has elapsed, there is no demand for operation of thecompressor motor because the thermostat, in responding to temperaturechanges, has failed to become actuated in the meantime, the compressormotor will remain released. Thus, in accordance with this invention, thecompressor motor may be brought into operation only after the equipmenthas been kept idle for the predeter- 2 mined time interval, and it willcontinue to remain idle thereafter unless there has meanwhile been acall for re-operation by, for example, the thermostat control equipmentupon the expiration of the predetermined time interval.

It is, therefore, still another object of this invention to associatethe timing or delay circuit of this invention with a load, such as acompressor motor, so arranged that the timing circuit will be activatedto establish a predetermined time interval and the compressor motor willbe held unoperated during the tolling of the time interval, but thecompressor motor will become operated only upon the expiration of thetime interval if the thermostat is closed. Hence, each release of thecompressor motor will re-start the tolling of the time interval, but themotor must await the expiration of the time interval before the motorcan be re-started into operation (again assuming the thermostat isclosed).

In accordance with the present invention, the chattering of a relaycontact, or the sudden changes in the temperature in the vicinity of athermostat causing the thermostat to operate and release frequentlyduring a brief period of time, are minimized or eliminated byassociating a special timing circuit with the compressor motor so as toautomatically prevent the compressor motor from operating until asufficiently long interval of time, such as five minutes, has expired.

This invention will be better and more clearly understood from thefollowing more detailed description and explanation hereinafterfollowing when read in connection with the accompanying drawing, inwhich FIG. 1 illustrates schematically general circuitry to be employedfor carrying out the principles of this invention;

FIG. 2 schematically illustrates a solid state timing circuit forestablishing a sufficiently long time interval, such as five minutes, inan arrangement such as that of FIG. 1; and

FIG. 3 illustrates schematically another solid state timing circuit forestablishing a relatively shorter time interval, such as two minutes, toaccomplish another objective in an arrangement such as that of FIG. 1.

Referring to FIG. 1 of the drawing, there is shown a schematic circuitinterconnecting two timing mechanisms TMS and TM2 with a compressormotor CPM of an air-conditioning system and a source of power G, such as24 volt AC. power. The interconnecting circuit includes a first timerswitch T5 associated with the timer mechanism TMS and a second timerswitch T2 associated with the timer mechanism TMZ. The circuitry alsoincludes a relay RK and a thermostat TH, both of which may beconventional forms of equipment. The timer T5 includes a normally openswitch S5 but, when power is applied to the terminals E4 and E5 of thetimer mechanism TMS, the switch S5 will be closed after a predeterminedinterval of time, such as five minutes, has elapsed. The timer T2includes a switch S2 which is normally closed but, when power is appliedto the terminals E1 and E2 of the timer mechanism TM2, the switch S2will be openedbut only after the second predetermined time interval,such as 2 minutes, has elapsed.

As will be explained, the compressor motor CPM can be operated by powersupplied by the generator but only after the timer switchSS has beenclosed and only after the thermostat TH has also been closed by a callfor airrconditioning power. But, when the motor has stopped operatingdue to the release of thermostat TH, the timer T will be re-energizedand will become closed only after the first predetermined interval hasagain expired. Then and only then may the compressor motor CPM bere-operated. The compressor motor CPM cannot be re-operated (except bymeans of a test switch SW1) unless the timer switch T5 has gone throughits time cycle and become closed.

The timer switch S2 of timer mechanism TM2 will be normally closed whenthe power of generator G is applied to the terminals El and E2 of thetimer mechanism TM2, and switch S2 will become opened at the end of asecond and different predetermined interval of time, for example, twominutes. If, in the meantime, air-conditioning fluid, such as freon, hasbeen supplied to the air-conditioning system in sufficient amount so asto raise the pressure of the fluid to a desired magnitude, the switchLPS will then be closed and will allow the compressor motor CPM tooperate. If the fluid pressure has not reached its desired value, theswitch LPS will be released, hence preventing the compressor motor CPMfrom continuing its operation.

As soon as the motor CPM has stopped operating while the generator G mayremain connected to the terminals E4 and E5 of the timer mechanism TMS,the generator terminal G1 will be connected to terminal E4 and at thesame time the generator terminal G2 will be connected to terminal E5over the circuit of conductor L2, the armature and back contact K2 ofrelay RK. The switch mechanism TMS is so arranged, as will be explainedin reference to FIG. 2, that the normally open switch contact S5 will beclosed after a predetermined interval of time, such as five minutes.Hence, the timer contact TS will be prepared for providing the circuitryto the compressor motor CPM only after the expiration of the necessarytime interval.

The generator G will, at the same time, supply voltage to the terminalsE1 and E2 of the timer mechanism TM2 when thermostat TH is closed andrelay RK is operated. Terminal G1 of generator G will be con nected toterminal E1 over a circuit which includes conductor Ll, the armature andmake contact Kl of relay RK, and thermostat TH. As will be more clearlyexplained in connection with FIG. 3, the switch S2 will be closed andremain closed for a predetermined interval of time, such as 2 minutes,after which switch S2 will be opened. During this interval, thecompressor motor CPM will be energized by generator G through timer T2and will remain energized if the fluid pressure has been raised enoughto close contact LPS.

Assume now that the thermostat TH is in its open position because therehas been no call for air-conditioning service. Terminal G1 of generatorG will be connected to terminal E4 of the timer mechanism TMS, while theterminal E5 of the timer mechanism TMS will be connected to the terminalG2 of generator G through the back contact and armature K2 of relay RKand conductor L2. Thus, at the end of the first predetermined timeinterval, the switch S5 will be closed. Notwithstanding the closure ofswitch S5, the compressor motor CPM will remain unoperated unlessthermostat TH has been operated in response to a call forair-conditioning.

a call for cooling of the thermostat closure of the contact of armatureK3 of relay RK will.

complete the circuit between the generator G and the compressor motorCPM over a path which includes the conductor L5. Hence the motor CPMwill operate and continue to operate as long as the thermostat THcontinues to call for power, provided the fluid pressure exceeds apredetermined value.

With the contacts of thermostat TH closed, the operation of relay RKwill close its contact K1 and provide a locking circuit to hold therelay RK operated. The locking circuit shorts the path between terminalsE4 and E6 through contact K1, thus self-latching relay RK. Relay RK willcontinue to remain operated if thermostat TH remains closed. At the sametime, the opening of contact K2 of relay RK due to the operation ofrelay RK will disconnect the generator G from the timer mechanism TM5.Hence, the timer mechanism TMS will be released to its normally openposition and remain in that position to provide another time interval.

As already explained, power is also supplied initially to the terminalsE1 and E2 of the timer mechanism TM2 and, therefore, the normally closedswitch S2 provides a short-circuit across the fluid switch LPS. When thepressure has built up sufficiently, switch LPS closes. Hence, theair-conditioning system will operate for a period, such as 2 minutes.After the 2 minute interval has expired, and if in the meantime thefluid pressure has not built up sufficiently, then switch contact LPSwill remain open, opening the circuit to the winding of relay RK and, inturn, opening the circuit of compressor CPM. Hence, the compressor motorCPM cannot operate in the absence of sufficient fluid pressure.

After sufficient cooling has developed so that the thermostat TH hasopened its contacts, relay RK will be released. The release of thecontact K3 of relay RK will cause the compressor motor CPM to stop dueto the opening of its operating circuit. Upon the opening of contact K1and the closure of contact K2 of relay RK, the timer T5 will again beenergized to start the same time interval normally provided by timer T5,namely, a predetermined interval of, for example, 5 minutes. The switchS5 can be closed only after the predetermined time interval has expired.Hence, the compressor motor CPM cannot be started during that intervalbut only after that interval has expired.

A co-pending application of D. G. Harter, Ser. No. 31,199, filed Apr.23, 1970, and assigned to the same assignee, illustrates a compressorcontrol network employing two delay networks and a relay controlled by acontroller mechanism.

FIG. 2 schematically represents a circuit arrangement for the timermechanism TMS of FIG. 1 and it illustrates the condition of thecircuitry when relay RK of FIG. 1 is unoperated. Because the relay RK isunoperated, the generator G will be connected across the terminals E4and E5. A rectified voltage will produce a DC charge on electrolyticcapacitor C1, the rectified voltage arising from the inclusion of therectifier CR1 in the series circuit to the capacitor C1 and resistors R1and R16. At the same time, a DC voltage will be built up on the anode Aof the transistor Q1, the positive voltage being transmitted through theresistor R3. Moreover, a positive voltage will also be applied to thegate G of transistor-Q1, this voltage being applied through resistor R4and tapp d from. potentiometer R5 and thensupplied'through resistor R13to the gate G.

The two voltages, bothpositive, will be applied to the respectiveelectrodes A and G of transistor Q1. The

voltage applied to gate G reaches its steady state value promptly butthe voltageon anodeA of .transistor Q1 rises more slowly due principallytothe capacitor C2. Afterthe predetermined interval, such as 5 minutes,the voltage on electrode A will be so much higher than that on electrodeG thatthe transistor Q1 will become conductive. When this happens, thepositive voltage applied to the capacitor C2 will be fed through theterminals A and K of transistor Q1 and thence'through resistor R12 tothe gate G. ofSCR Q2. The applied positive voltage will render thesiliconcontrolled rectifier Q2 conducting. When this happens, a pathwill be established through theelectrodes X and G of triac TR, resistorR10, and electrodes A and K of silicon controlledrectifierQZ to ground.Theflowof current in the latter path will render .the triac TRconducting.

Upon the'triac TR becoming conductive (and assuming that the lowpressure'switchLPS is closed and that the contacts of thermostat TH areclosed), powenwill then be fed from the source Gthrough the electrodes Xand Y of the triac TRto-thewinding of the relay RK which, as shown inFIG. .1, is connected to the terminals E5 and E6. This causes the relayRK to become operated. If the .contact'KZ of relay RKremains open for apredetermined time intervahsuch as a lOOrnilliseconds, .thereby denotingthe disconnection of generator Gfrom thecircuit, the timer T5 will bereset and it will go throughits .cycle,'previously described, promptlyupon the closure of the contact K2. The compressor motor CPM can bereconnected after the passage of thelong time interval as alreadyexplained.

In resetting thecircuitry of FIG. 1 after the switch T5 has been closed,all of the capacitorsCl to C5 of FIG. 2 will be discharged (exceptcapacitor C2) through the resistive paths shunting these capacitors.Capacitor C2 discharges through rectifier CR2 and SCR device Q2. Theother capacitor discharge paths are clearly shown and need not bedetailed. Moreover, the transistor Q1 and the SCR Q2'will becomenon-conductive and, at the same time, the triac TR will return to itsinitial nonconductive state.

. The circuitry associated with transistor O1 in the FIG, 2 arrangementisunique in having two voltages applied to its electrodes A and G whichrise at different rates, the voltage applied to anode A rising at aslower rate than the voltage. on; gate G. When the voltage on anode Abecomes greaterthan'the voltage on gate G by a predetermined amount, andonly then, the transistor Q1 will become conductive. This will be thecase at normal temperatures. However, at sub-normal temperatures towhich the circuit of FIG. 2 may be ex- 6 posed, such as minus 'ZSC, the.switching current available to the transistor Q1 maybe-insufficient torender it conductive. Accordingto this invention, this condition may beovercome by'the employment of capacitor C3 in the ,circuiLCapacitoriCSisconnected sistor R16 serves to further reduce thevoltage on gate Gwith respect to the voltage on the anode A of transistor Q1. and,causestransistor Q1 to become conductive under the abnormal temperatureconditions.

The addition of capacitor C3:to thecircuitry ofv FIG. 2 provides asimple'and inexpensive-arrangement.for

keeping the timer T5 operativeeven-at sub-normal temperatures suchasminus 25C or lower. Alternative methods may be developed to accomplisha similar purpose, but theywould usually requirethe employment of one ormore additional transistors in tandem with transistor 0-] to introducethe necessary-switching current to operate thenetwork of FIG.. 2.

.FIG. 3 schematically illustratesthetimer mechanism generallyrepresented as TMZ -in i-FIG. 51. This timer mechanism parallels the.sWitchiILPS of FIG. 1' which is normally open and becomes closed for asubstantial I predetermined .time interval in response to the: attainment of sufficient pressure in the {fluid fed. to the conventionalcompressor of an air-conditioningsystem.

, FIG..3)is,in many respects," similar to-.the.-arrangement of FIG. 2,except that an additionaltransistorQ4 and appropriate circuit elements:aretinserted between SCR device Q2 and triac TR of FlG. -2.-Transistor'Q4 operates as an inverter to rendertthetriac :TR non-conductive'.instead of conductive, and-vice .versa.

When SCR deviceiQZ of FIG.;3is in its conductive state, no current canflow to the 'base of transistor 04 and hence transistor Q4 willbenomcbnductingfiowever, as soon as SCR device Q2 becomesnon-conducting,the base B of transistor Q4-will receive current throughresistors .R15 and R8. This .current then renders transistor Q4conducting. Assoon as transistor Q4 becomes conducting, the triac'JTRwilla'become conducting by establishing .a path for1the flow of currentthrough electrodes Xand G of triac s'l'Randthrough the collectorandemitter electrodes ofztransistor to ground.

When the triac TR becomes conductive, its irnpedance willdrop off to anegligiblevalue. Hence, the winding of relay RK,which is.connectedatothe terminals E2 and E3, will be energized, as alreadyexplained in connection with FIG. 1.

One of the essential physical differences between the circuits of FIGS.2 and 3 is in the sizeslofitheir respective capacitors C2.ThecapacitofCZof FIG. 3 may have capacitance of about two microfarads,while the capacitor C2 of FIG. 2 may havea capacitance of about fivemicrofarads. Capacitor C2 is an important element in the circuit inestablishing the magnitude of the delay interposed by the timer circuit.

In each of FIGS. 2 and 3, a Zener diode Z is shown connected acrossresistor R16. This Zener diode limits the voltage drop across resistorR16 due to noise spikes and hence limits the magnitude of the feedbackpulses fed through capacitor C3 to the gate of transistor Q1. The Zenerdiode Z therefore prevents erratic timing due to noise or othersuperimposed voltages and this is a feature of this invention.

It will be apparent that this invention provides a feature forpreventing the compressor motor CPM from starting up due to a powerinterruption occurring during the timing cycle of timer TMS while thethermostat TH remains operated. If, during the timing cycle of timerTMS, power should be interrupted for a period of two seconds or longerdue, for example, to a lightning storm or to accidental circuit breakertripping, or the like, and then power reapplied, the motor CPM willremain released according to this invention until the completion of anew five minute interval again developed and established by the sametimer mechanism TMS now responding anew to the re-connected power supplycircuit after the lightning or other interruption has ceased.

The circuitry of this invention is provided for preventing theintermittent operation of the relay RK by jiggling or makingquickchanges in the condition of the thermostat TH during the overall timecycle that is required to operate the timer mechanism TMS. Thisarrangement prevents the motor CPM from being operated during any suchjiggling operation. The jiggling of the thermostat TH is one of severalmeans by which the operation of the motor CPM may be inadvertentlystarted and stopped and may therefore adversely introduce undesired andintermittent interruptions of motor CPM. In the absence of such jigglingor other interruptions, the compressor motor CPM will be operatedcontinually until. the thermostat TH is released.

The switch SW1, which is shown in FIG. 1, may be a conventional pushbutton controlled switch. When it is actuated, it serves to bypass partof the circuitry of the timer switch T5 of FIG. 2 and it, therefore,bypasses the usual timing cycle of, for example, 5 minutes. Thus, bypushing the switch button SW1, the triac TR will conduct, therebyoperating the relay'RK and causing the motor CPM to operate (assumingthat thermostat TH remains closed). The push button switch SW1 is,therefore, employed primarily for testing purposes.

While the invention has been described with respect to anair-conditioning system employing a compressor motor, this has beendescribed merely for illustration. The arrangement of this invention isequally applicable to any load device in place of the motor CPM, whetheremployed for air-conditioning purposes or for any other purpose.

While this invention has been shown and described in certain particulararrangements merely for illustration and explanation, it will beapparent that the arrangements of this inventionma'y be embodied in manyother and widely variedorganizations, all of which are provided for-thepurpose of establishing a time interval before a load device may beoperated, or for preventing the load device from operating untilsomespecified condition is satisfied, such as the advent of sufficientfluid pressure.

What is claimed is:

1. A regulating system including the combination of a source of power, aload, a switch interconnecting said source with said load to operatesaid load, means responsive to the operation of said switch to delay theinterconnection of said source to said load to operate said load after apredetermined time interval which is sufiiciently long as to preventrandom intermittent operation of the load, means to prevent theinterconnection of said source to said load to re-operate said loadwhile said switch is re-operated during said time interval, and means toprevent the reactivation of said load in response to an interruption ofthe interconnected circuit during said predetermined time interval, saiddelay means including a normally non-conductive device to which two D.C. voltages are supplied which rise in magnitudes at difierent rates torender said device conductive when the D. C. voltage difference reachesa predetermined value.

2. A regulating network according to claim 1 in which said switch andsaid delay means also includes a feedback path feeding additionalvoltage to said device supplied with DC. voltages.

3. A regulating network according to claim 1 in which the delay meansfor said switch includes means to render the delay network responsiveover a wide temperature range, said means including a feedback pathfeeding DC. voltage between the two electrodes to which the DC voltagesare applied.

4. The combination of a source of power a load, switch mechanisminterconnecting said source with said load, means responsive to theoperation of said switch mechanism to prevent the operation of said loadby power from said source during a predetermined time interval aftersaid switch mechanism has been operated, said means including means toprevent the reactivation of said load in response to an inadvertentinterruption of the interconnecting circuit during said predeterminedtime interval, said means including a device which receives two D. C.voltages which rise in magnitudes at different rates and activate thedevice when the difference between said two D. C. voltages reaches apredetermined value, said switching mechanism including means forsubstantially reducing the effect of noise currents on the operation ofsaid switch mechanism.

5. The combination of claim 4 in which the switch mechanism includes athermostat.

6. The combination of claim 4 in which the noise reducing meanscomprises a Zener diode in parallel with a resistor for feeding DC.voltage to the device.

7. Apparatus for protecting a motor against random start and stopoperations after said motor has been connected to its source of power,comprising means including a delay circuit coupling said motor to saidsource of power to introduce a delay of a predetermined time interval inthe operation of said motor, said delay circuit means having means fordeveloping two D.C. voltages which rise in magnitudes at different ratesand introduce the delay interval when the difference between said D.C.voltages reaches a predetermined magnitude, means responsive to anyinterruption of said interconnected circuit to deactivate said motor,and means to prevent the re-activation of said motor if there is anyinterruption of said interconnected circuit during said predeterminedinterval.

8. Apparatus according to claim 7 in which the ap paratus includes athermostat for responding to tem perature variations. i

9. Apparatus for rendering a transistor substantially independent ofwide temperature variations, the transistor including first, second andthird electrodes, comprisingmeans for applying between the first andsecond electrodes respective D.C. voltages which rise in magnitudes atdifferent rates, said transistor being rendered conductive when thevoltage difference between the first and second electrodes reaches apredetermined value, an output circuit connected between the first andthird electrodes, and means for feeding a negative voltage to the secondelectrode.

10. A delay circuit for introducing delay in the operation of a load,comprising a transistor having first, second and third electrodes, meansfor applying to the first and second electrodes, respectively, pulses ofDC. current which vary at different rates, the load being connected to asecond device, and means for rendering the operation of said delaycircuit substantially independent of wide temperature variations, saidmeans including a feedback path for applying a negative voltage to thesecond electrode.

11. A delay circuit according to claim 10 including means for renderingthe transistor conductive when the voltage applied to the firstelectrode exceeds that applied to the second electrode by apredetermined amount and for rendering the transistor non-conductivewhen said voltage is below said predetermined voltage.

12. A regulating system for an air-conditioner having a compressor towhich refrigerating fluid is transmitted and a motor for operating thecompressor, comprising switch mechanism interconnecting said motor toits source of power, means responsive to the operation of said switchmechanism to delay the interconnection of said motor to its source ofpower and thereby to delay the operation of said motor until theexpiration of a first predetermined time interval which is sufficientlylong so as to prevent random intermittent operation of said motor, saidresponsive means including a normally non-conductive device to which aresupplied two D.C. voltages which rise in magnitudes and which becomesconductive when the difference between the DC. voltages reaches apredetermined magnitude, and means to prevent the operation of saidmotor in response to the operation of said switch mechanism during asecond predetermined time interval to allow the pressure of the fluidsupplied to the compressor to reach a predetermined magnitude and toprevent the connection of said motor to said load in the absence of thepressure of said fluid reaching the said predetermined magnitude.

13. A regulating system according to claim 12 in which each means forintroducing a delay of a predetermined time interval in the operation ofsaid motor includes means to render said delay networks responsive overa wide temperature range.

14. A regulating system according to claim 12 in which the switchmechanism includes a thermostat.

1. A regulating system including the combination of a source of power, aload, a switch interconnecting said source with said load to operatesaid load, means responsive to the operation of said switch to delay theinterconnection of said source to said load to operate said load after apredetermined time interval which is sufficiently long as to preventrandom intermittent operation of the load, means to prevent theinterconnection of said source to said load to re-operate said loadwhile said switch is re-operated during said time interval, and means toprevent the reactivation of said load in response to an interruption ofthe interconnected circuit during said predetermined time interval, saiddelay means including a normally non-conductive device to which two D.C. voltages are supplied which rise in magnitudes at different rates torender said device conductive when the D. C. voltage difference reachesa predetermined value.
 2. A regulating network according to claim 1 inwhich said switch and said delay means also includes a feedback pathfeeding additional voltage to said device supplied with D.C. voltages.3. A regulating network according to claim 1 in which the delay meansfor said switch includes means to render the delay network responsiveover a wide temperature range, said means including a feedback pathfeeding D.C. voltage between the two electrodes to which the D.C.voltages are applied.
 4. The combination of a source of power a load,switch mechanism interconnecting said source with said load, meansresponsive to the operation of said switch mechanism to prevent theoperation of said load by power from said source during a predeterminedtime interval after said switch mechanism has been operated, said meansincluding means to prevent the reactivation of said load in response toan inadvertent interruption of the interconnecting circuit during saidpredetermined time interval, said means including a device whichreceives two D. C. voltages which rise in magnitudes at different ratesand activate the device when the difference between said two D. C.voltages reaches a predeterMined value, said switching mechanismincluding means for substantially reducing the effect of noise currentson the operation of said switch mechanism.
 5. The combination of claim 4in which the switch mechanism includes a thermostat.
 6. The combinationof claim 4 in which the noise reducing means comprises a Zener diode inparallel with a resistor for feeding D.C. voltage to the device. 7.Apparatus for protecting a motor against random start and stopoperations after said motor has been connected to its source of power,comprising means including a delay circuit coupling said motor to saidsource of power to introduce a delay of a predetermined time interval inthe operation of said motor, said delay circuit means having means fordeveloping two D.C. voltages which rise in magnitudes at different ratesand introduce the delay interval when the difference between said D.C.voltages reaches a predetermined magnitude, means responsive to anyinterruption of said interconnected circuit to de-activate said motor,and means to prevent the re-activation of said motor if there is anyinterruption of said interconnected circuit during said predeterminedinterval.
 8. Apparatus according to claim 7 in which the apparatusincludes a thermostat for responding to temperature variations. 9.Apparatus for rendering a transistor substantially independent of widetemperature variations, the transistor including first, second and thirdelectrodes, comprising means for applying between the first and secondelectrodes respective D.C. voltages which rise in magnitudes atdifferent rates, said transistor being rendered conductive when thevoltage difference between the first and second electrodes reaches apredetermined value, an output circuit connected between the first andthird electrodes, and means for feeding a negative voltage to the secondelectrode.
 10. A delay circuit for introducing delay in the operation ofa load, comprising a transistor having first, second and thirdelectrodes, means for applying to the first and second electrodes,respectively, pulses of D.C. current which vary at different rates, theload being connected to a second device, and means for rendering theoperation of said delay circuit substantially independent of widetemperature variations, said means including a feedback path forapplying a negative voltage to the second electrode.
 11. A delay circuitaccording to claim 10 including means for rendering the transistorconductive when the voltage applied to the first electrode exceeds thatapplied to the second electrode by a predetermined amount and forrendering the transistor non-conductive when said voltage is below saidpredetermined voltage.
 12. A regulating system for an air-conditionerhaving a compressor to which refrigerating fluid is transmitted and amotor for operating the compressor, comprising switch mechanisminterconnecting said motor to its source of power, means responsive tothe operation of said switch mechanism to delay the interconnection ofsaid motor to its source of power and thereby to delay the operation ofsaid motor until the expiration of a first predetermined time intervalwhich is sufficiently long so as to prevent random intermittentoperation of said motor, said responsive means including a normallynon-conductive device to which are supplied two D.C. voltages which risein magnitudes and which becomes conductive when the difference betweenthe D.C. voltages reaches a predetermined magnitude, and means toprevent the operation of said motor in response to the operation of saidswitch mechanism during a second predetermined time interval to allowthe pressure of the fluid supplied to the compressor to reach apredetermined magnitude and to prevent the connection of said motor tosaid load in the absence of the pressure of said fluid reaching the saidpredetermined magnitude.
 13. A regulating system according to claim 12in which each means for introducing a delay of a predetermineD timeinterval in the operation of said motor includes means to render saiddelay networks responsive over a wide temperature range.
 14. Aregulating system according to claim 12 in which the switch mechanismincludes a thermostat.